The reaction of primary or secondary amines with carboxylic anhydrides represents a classical preparation of amides. However, in moving from classical chemistry to practical commercial considerations the medium in which the reaction is conducted becomes significantly more important. Means must be provided for bringing the reactants together in a manner which ensures substantially complete reaction, allows for the practical handling of the reactants and the reaction mixture, and provides for the recovery of the desired reaction product in a practically handleable form. Typically this has involved dissolving both the amine and carboxylic anhydride in a process solvent followed by isolation of the amide from the process solvent. Of course it is also possible to simply mix the two reactants in a molten state if they are sufficiently miscible and if there is a set of convenient reaction conditions (temperature and pressure) under which both reactants are in the molten state. However, in such a case the recovery of the finished product may present significant problems particularly if it is solid under these reaction conditions.
An object of the present invention is to provide a procedure whereby aromatic amines may be reacted with acetic anhydride without the use of a process solvent and without the necessity of bringing both reactants to a molten or liquid state. A further object of the present invention is to provide a procedure whereby the product amide may readily be recovered or isolated as free-flowing particles. Another object of the present invention is to provide a procedure whereby the product amide may be isolated by the simple evaporation of acetic acid and acetic anhydride.